public void Add()
{
var list1 = new DList <DObject>();
list1.Add(new { value = "1" });
list1.Single().GetString("value").ShouldBe("1");
Should.Throw <InvalidCastException>(() => list1.Add(2));
var list2 = new DList <int>();
list2.Add(1);
list2.Single().ShouldBe(1);
Should.Throw <InvalidCastException>(() => list2.Add(new { value = "2" }));
}